# Immediate Effect of Four Exercises on Linea Alba Thickness, Distortion and Inter‐Recti Distance in Parous Women

## TL;DR

This study compares how four abdominal exercises affect the thickness and distortion of the linea alba in women who have given birth.

## Contribution

The study identifies exercise-specific mechanical responses of the linea alba and transversus abdominis muscle during common abdominal exercises.

## Key findings

- The crunch exercise reduced inter-recti distance but increased linea alba distortion.
- De Gasquet exercise preserved linea alba thickness and minimized distortion.
- Transversus abdominis activation varied by exercise and influenced linea alba behavior.

## Abstract

This cross‐sectional study assessed the impact of four abdominal exercises (crunch, abdominal drawing‐in maneuver [ADIM], pelvic floor muscle contraction, and de Gasquet basic exercise) on inter‐recti distance (IRD) and linea alba (LA) distortion and thickness in parous women.

Parous women underwent ultrasound assessment during four abdominal exercises. The primary outcome was IRD at supra‐ and infraumbilical levels. Secondary outcomes were LA distortion and thickness. Transversus abdominis (TrA) activation was assessed simultaneously. Exercises were compared using linear mixed‐effects models and Tukey‐adjusted pairwise tests.

Fifty‐four parous women participated. Supraumbilically, the crunch showed the greatest IRD decrease (EMM + 2.48 mm), but this was not significantly different from ADIM, pelvic floor muscle contraction, or de Gasquet exercise (Tukey p ≥ 0.07). The crunch was associated with increased LA distortion during the exercise compared with other exercises (supra: + 0.26 ± 0.05; infra: + 0.35 ± 0.07 distortion units; both p < 0.001), while the other three exercises reduced or maintained distortion during the exercise. Supraumbilical LA thickness increased during crunch compared with the other exercises (Tukey p ≤ 0.05). TrA effects were exercise‐specific: greater TrA thickening was associated with greater IRD decrease during ADIM, whereas lower TrA thickening was associated with greater IRD decrease during crunch.

The crunch showed the largest supraumbilical immediate reduction in IRD but was accompanied by increased LA distortion. In contrast, the other three exercises were associated with smaller IRD changes and lower distortion. Lower TrA activation during crunch was associated with increased LA deformation, and apparent medial convergence of the rectus abdominis during the exercise.

This research was registered on ClinicalTrials (NCT04501302)

During the exercise, the crunch tended to show the greatest immediate reduction in supraumbilical inter‐recti distance; however, this change was not significantly different from abdominal drawing‐in, pelvic floor muscle contraction, or de Gasquet exercises, and was accompanied by increased linea alba distortion.Lower transversus abdominis thickening during crunch was associated with greater inter‐recti distance decrease and increased linea alba distortion, suggesting an association between transversus abdominis activation and linea alba mechanical behavior during this exercise.De Gasquet exercise showed mechanical responses similar to abdominal drawing‐in maneuver and pelvic floor muscle contraction, with limited distortion and preservation of linea alba thickness and inter‐recti distance.Observed variations in linea alba behavior and transversus abdominis activation during the exercises indicate exercise‐specific immediate mechanical responses and provide a basis for individualized assessment and future research.

During the exercise, the crunch tended to show the greatest immediate reduction in supraumbilical inter‐recti distance; however, this change was not significantly different from abdominal drawing‐in, pelvic floor muscle contraction, or de Gasquet exercises, and was accompanied by increased linea alba distortion.

Lower transversus abdominis thickening during crunch was associated with greater inter‐recti distance decrease and increased linea alba distortion, suggesting an association between transversus abdominis activation and linea alba mechanical behavior during this exercise.

De Gasquet exercise showed mechanical responses similar to abdominal drawing‐in maneuver and pelvic floor muscle contraction, with limited distortion and preservation of linea alba thickness and inter‐recti distance.

Observed variations in linea alba behavior and transversus abdominis activation during the exercises indicate exercise‐specific immediate mechanical responses and provide a basis for individualized assessment and future research.